DXdao guild — zero totalLocked lets a stranger pass a paying proposal

Source & credit. Reproduction of a public audit finding curated by AuditVault — the original finding: 19347-zero-totallocked-allows-everyone-to-create-proposals-sigmapr. Standalone Foundry PoC and full write-up: 19347-zero-totallocked-allows-everyone-to-create-proposals-sigmapr_exp in the evm-hack-registry mirror.

Vulnerability classes: vuln/governance/proposal-manipulation

Key info#


Protocol	DXdao ERC20Guild
Finding	Sigma Prime, AuditVault 19347
Vulnerable code	`getVotingPowerForProposalCreation` is `totalLocked / 100`
Harm	A stranger with no lock passes a proposal that pays 100e18
Chain	local synthetic

TL;DR#

Creation power is totalLocked / 100. With nothing locked that value is 0. A stranger whose own lock is also 0 passes locked >= power and createProposal transfers the guild's 100e18.

The control requires the caller to hold a lock of at least 1 ether and totalLocked of at least 1 ether. The stranger is rejected and the 100e18 stays.

The vulnerable code#

SOLIDITY

function getVotingPowerForProposalCreation() public view returns (uint256) {
    return totalLocked / 100;
}

require(locked[msg.sender] >= getVotingPowerForProposalCreation(), "create");
// @> VULN: creation power is zero when nothing is locked, so this pay runs for a stranger.
asset.transfer(to, amount);

Root cause#

The minimum is a percentage of the current locked base. A zero base produces a zero minimum. The comparison 0 >= 0 succeeds, so the proposal pays out.

Preconditions#

totalLocked is 0. The caller has no lock. The guild holds 100e18. No role is required.

Attack walkthrough#

The guild is funded with 100e18. totalLocked is 0.
Creation power reads as 0.
The stranger's lock is 0, which meets that power.
createProposal transfers 100e18 to the stranger.
On the fixed guild the same call reverts because the caller has no 1 ether lock. The guild still holds 100e18.

Diagrams#

flowchart TD A["totalLocked is 0 so creation power is 0"] --> B["A stranger with no lock calls createProposal"] B --> C["0 is greater than or equal to 0 so the check passes"] C --> D["VULN: the proposal transfers 100e18"] D --> E["The stranger holds 100e18 and the guild holds 0"]

Impact#

A stranger who never locked tokens receives 100e18 from the guild. Every later call with the same zero base can pay again until the guild is empty.

Remediation#

Floor the creation power at a non-zero lock. totalLocked == 0 must not make 0 >= 0 a passing check.

How to reproduce#

BASH

cd 19347-zero-totallocked-allows-everyone-to-create-proposals-sigmapr_exp
forge test -vv

test_zero_lock_pays_the_stranger_100e18 asserts the 100e18 payment. test_control_requires_a_lock asserts the call reverts.

Sources#

AuditVault finding: https://github.com/Auditware/AuditVault/blob/main/findings/19347-zero-totallocked-allows-everyone-to-create-proposals-sigmapr.md
Sigma Prime report: https://github.com/sigp/public-audits/blob/master/dxdao/erc20-guild/review.pdf

Sources & further analysis#

Reproductions & code

Standalone PoC + full trace: 19347-zero-totallocked-allows-everyone-to-create-proposals-sigmapr_exp (evm-hack-registry mirror).
AuditVault finding: 19347-zero-totallocked-allows-everyone-to-create-proposals-sigmapr.

Alerts & third-party analyses

Web3Sec X hacked database: search.
Rekt leaderboard: search.
Solodit incident search: search.

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